1. Field of the Invention
The present invention relates to a hollow golf club head.
2. Description of the Related Art
A conventional hollow golf club head includes a head main body 14 having a face opening portion 12 on a face side 10 and a face member 16 for closing the face opening portion 12, as shown in FIGS. 4 and 5 (e.g., refer to JP-A-2001-137396).
The hollow golf club head, particularly the recent hollow golf club head made of titanium alloy, can be further enlarged owing to the improved manufacturing technologies. Owing to the enlargement of the head as well as the deeper center of gravity, the researches for improving the easiness of the head to return at the time of hitting a ball and the easiness of the ball to go up have progressed.
The hollow golf club head as shown in FIGS. 4 and 5 is preferable if the center of gravity position of the head on the face side (point where the actual center of gravity of the golf club head is vertically projected onto the face side) and the center of figure position of the face member are as close as possible, especially if the center of gravity position of the head on the face side and the center of figure position of the face member are coincident, because there is greater deflection of the face member at the time of hitting the ball and the flying distance and the feeling of hitting are improved. The center of figure means a point that corresponds to the point of application when the resultant force is obtained by considering the area of figure as a force. Moreover, the actual center of gravity of the golf club head is located in a hollow portion of the golf club head as indicated by sign G in FIG. 5.
However, since the head has the deeper center of gravity, the head center of gravity position A on the face side is considerable higher than the center of figure position B of the face member, as shown in FIGS. 4 and 5. Thereby, the face member 16 was not sufficiently flexed when hitting a golf ball, so that the flying distance was less sufficient and the feeling of hitting became bad occasionally.